State of the art Head Up Display (HUD) and Head Mounted Display (HMD) systems may use combiners disposed in the optical path between a user and a windshield, such as on a vehicle or airplane, to overlay synthetic imagery on an image of the outside scenery. Some combiners may have a partially reflective, inward facing surface, whereas some combiners may form the synthetic images in their bulk. Those combiners using a partially reflective, inward facing surface typically have the inward surface made concave, thus acting as an eyepiece. To render a powerless transmissive optic, the outward facing surface is typically made convex. However, the fabrication of such three-dimensional combiners is both complex and expensive.